A construction machine such as a wheel loader is frequently used for a work of transporting or loading soil. In more detail, after the wheel loader transports the soil up to a position near a transportation means such as a truck, the wheel loader raises a boom and thereafter, full-dumps a bucket to drop the soil to the transportation means. In addition, the wheel loader moves the bucket back to a return-to-dig position and drops the boom. Thereafter, the wheel loader moves to a place where the soil is accumulated, loads the soil in the bucket, and adjusts the bucket to a full-crowd position. Such work is repeated multiple times until the soil is filled in the transportation means. Therefore, a wheel loader operator should repeatedly perform an operation of raising and dropping the bucket to the transportation means.
FIG. 1 is a diagram illustrating configurations of a general wheel loader and a wheel loader detent apparatus in the related art.
As shown in FIG. 1, the general wheel loader includes a bucket 111, a bucket cylinder 112 for dumping or crowding the bucket 111, and a boom 113 for raising or dropping the bucket 111.
In order to facilitate the operation of the bucket 111 which the wheel loader raises and drops to the transportation means, the wheel loader detent apparatus in the related art includes a mechanism unit 114 that moves in conjunction with movement of the bucket 111, an electromagnet 123, a power 121 for supplying power to the electromagnet 123, a ground 124 for grounding the electromagnet 123, and a non-contact proximity switch 122.
The non-contact proximity switch 122 switches connection between the power 121 and the electromagnet 123 depending on whether or not the mechanism unit 114 is in the proximity of the non-contact proximity switch 122. That is, when the mechanism unit 114 is not in the proximity of the non-contact proximity switch 122, the non-contact proximity switch 122 connects the power 121 to the electromagnet 123. On the contrary, when the mechanism unit 114 is in the proximity of the non-contact proximity switch 122, the non-contact proximity switch 122 does not connect the power 122 to the electromagnet 123. Herein, the non-contact proximity switch 122 may include a metal sensor that can sense whether or not the mechanism unit 113 is in the proximity of the non-contact proximity switch 122.
While the non-contact proximity switch 122 is turned on and the power 121 is supplied to the electromagnet 123, when an operator makes a joystick lever 131 to be in the proximity of a crowd-direction electromagnet 123, the electromagnet 123 fixes the joystick lever 131 by using magnetic force by current of the power 121.
Thereafter, when the non-contact proximity switch 122 is turned off as the mechanism unit 114 moves while the joystick lever 131 is fixed, the power 123 is not supplied to the electromagnet 123, and as a result, the electromagnet 123 does not fix the joystick lever 131 and returns the joystick lever 131 to a neutral position.
As such, the wheel loader detent apparatus in the related art latches the joystick lever 131 by means of the electromagnet 123 when the wheel loader joystick lever 131 is positioned at an upper limit or lower limit position. In the detent apparatus of the wheel loader in the related art, when the mechanism unit 114 reaches a predetermined position, the power 121 of the electromagnet 123 is cancelled to return the joystick lever 131 to the neutral position. Herein, the predetermined position is a position 101 for loading a cargo. The detent apparatus of the wheel loader allows a working machine (for example, a bucket cylinder and a boom cylinder) to be arbitrarily driven by controlling the joystick lever 131 out of a detent section even though an operator does not consecutively maintain the position of the joystick lever 131.
A detent position of the wheel loader detent apparatus in the related art is one spot and is set as a return to dig (hereinafter, referred to as a ‘loading position’) 101 for loading the cargo. That is, the wheel loader detent apparatus serves to detent the bucket 111 to the loading position 101 during a dump or crowd operation.
FIG. 2 is an explanatory diagram of an electromagnet on/off operation from a full dump position to a full crowd position by the wheel loader detent apparatus in the related art.
As shown in FIG. 2, when the operator classifies an operation of raising or dropping the bucket 111 of a wheel loader to the transportation means, the operation is classified into a section 210 in which the electromagnet 123 is turned on and a section 220 in which the electromagnet 123 is turned off. The section 210 where the electromagnet 123 is turned on is from a full dump position 201 to a loading position 202 of the bucket 111. On the contrary, the section 220 where the electromagnet 123 is turned off is from the loading position 202 to a full crowd position 203.
In the section 210 where the electromagnet 123 is turned on, the non-contact proximity switch 122 supplies the power 121 to the electromagnet 123. Then, the electromagnet 123 fixes the joystick lever 131 by using the magnetic force of the electromagnet 123 when the joystick lever 131 is in the proximity of the electromagnet 123. That is, the joystick lever 131 is latched in a crowd direction by the electromagnet 123.
In the section 220 where the electromagnet 123 is turned off, the non-contact proximity switch 122 interrupts the supply of the power 121 to the electromagnet 123. Then, the electromagnet 123 returns the joystick lever 131 fixed during the section “210” to the neutral position. When the joystick lever 131 is returned to the neutral position, the bucket 111 which is driven by latching the joystick lever 131 during the section “210” stops at the loading position 202.
Herein, the non-contact proximity switch 122 cannot but interrupt the supply of the power 121 to the electromagnet 123 from the loading position 202 of the bucket 111 to the full crowd position 203. That is, the wheel loader detent apparatus in the related art cannot but set the detent position as only one position (loading position 202). Therefore, the wheel loader detent apparatus in the related art cannot provide a detent function at the full crowd position 203.
In this regard, the operator performs the driving of the wheel loader and the dumping and crowding works of the bucket 111 simultaneously. When there is no detent function at the full crowd position 203, the operator should move a handle of the wheel loader and the joystick lever 131 simultaneously, and thus, it is hard for the operator to easily perform the works.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.